Transparent laminate, image display device, double-sided antireflection laminate, and facial transparent protector

The present application enjoys the benefit of priority to the prior Japanese Patent Application No. 2020-113538 (filed on Jun. 30, 2020), the entire disclosure of which is incorporated herein by reference.

The present invention relates to a transparent laminate, an image display device, a double-sided antireflection laminate, a double-sided antireflection laminate, and a facial transparent protector.

In recent years, image display devices that can be used outdoors, such as digital signage (electronic billboards), have been developed. In some cases, an image display device to be used outdoors has a front plate arranged on the observer side of its display panel via an air layer (air gap) so as to have higher durability.

The front plate is usually constituted by a glass plate. In some cases, an antireflection film is provided between the glass plate and the display panel to inhibit the reflection of external light (see, for example, Patent Literature 1).

However, an image display device to be used outdoors is not configured to be anti-fogging although configured to be rainproof and windproof. In particular, an image display device the structure of which has an air layer between the front plate and the display panel results in containing a larger amount of moisture in the air layer, when used outdoors. Because of this, providing an antireflection film on the front plate in such a manner that the antireflection film is on the display panel side will undesirably cause the moisture in the air layer to fog the surface of the antireflection film (specifically the surface of a low-refractive-index layer) during use of the image display device, decreasing the luminous reflectance of the surface of the antireflection film, and thus decreasing the clearness, visibility, and transmission of an image. In a large image display device in particular, the surface of a part of the antireflection film will be fogged, thereby decreasing the clearness of a part of an image, thus resulting in exhibiting unevenness due to a difference in the clearness from another part of the image in some cases.

At present, a new type of coronavirus is raging all over the world. It is known that a new type of coronavirus or the like causes infection via droplets. To prevent this droplet infection, a conversation may be carried out with a facial transparent protector such as a face shield put on or with a transparent partition or the like in between. In scenes where various types of persons come in contact with each other, such protective equipment is required in light of the prevention of infection with another type of virus and in light of hygiene, for example, the prevention of smudging.

However, carrying out a conversation across a facial transparent protector or a transparent partition will undesirably cause the reflection of light to make it difficult to see the movement of the mouth, and in addition, cause the exhaled air to fog the facial transparent protector or the like, giving a sense of unease or stress to the other person conversing.

The present invention has been made to solve the above-mentioned problems. That is, an object is to provide: a transparent laminate that has an antireflection ability and an excellent anti-fogging ability, and is less prone to change in luminous reflectance even in an environment liable to fog; an image display device and a double-sided antireflection laminate that each include the transparent laminate; and a facial transparent protector including the double-sided antireflection laminate.

The present invention makes it possible to provide: a transparent laminate that has an antireflection ability and an excellent anti-fogging ability, and is less prone to change in luminous reflectance even in an environment liable to fog; an image display device and a double-sided antireflection laminate that each include the transparent laminate; and a facial transparent protector including the double-sided antireflection laminate.

A transparent laminate, a double-sided antireflection laminate, an image display device, and a facial transparent protector according to an embodiment of the present invention will now be described with reference to the drawings. As used herein, the terms “film” and “sheet” are not distinguished from each other on the basis of the difference in naming alone. For example, the term “film” is thus used to refer inclusively to a member called a sheet.is a schematic block diagram of a transparent laminate according to the present embodiment.toare schematic block diagrams of another transparent laminate according to the present embodiment.is a schematic block diagram of an image display device according to the present embodiment.is a schematic block diagram of a facial transparent protector according to the present embodiment.is a schematic block diagram of a double-sided antireflection laminate depicted in.toare schematic block diagrams of other double-sided antireflection laminates according to the present embodiment.is a schematic block diagram of a single-sided antireflection laminate according to the present embodiment.

<<<Transparent Laminate>>>

A transparent laminatedepicted inis a transparent laminate having an antireflection ability and an anti-fogging ability. That is, the transparent laminatefunctions as an antireflection film and an anti-fogging film. Being “transparent” as used herein can be transparent enough to achieve a transmitting visibility in accordance with the use.

The transparent laminateincludes a base material, a functional layer, and a low-refractive-index layerhaving a refractive index lower than the refractive index of the functional layer, in this order. The low-refractive-index layeris adjacent to the functional layer. The transparent laminateincludes the base material, or optionally does not include the base material. In addition, the low-refractive-index layermay have at least one or more other functional layers provided thereon.

The surfaceA of the transparent laminatedepicted inis the surfaceA of the low-refractive-index layer. As used herein, the word “surface” of the transparent laminate is used to mean the low-refractive-index layer side surface of the transparent laminate. The opposite face of the transparent laminate from the surface is referred to as the “back surface” to be distinguished from the surface of the transparent laminate. The back surfaceB of the transparent laminateis the second faceB of the base material. In cases where the low-refractive-index layerhas at least one or more other functional layers provided thereon, the surface of the transparent laminate is the surface of the uppermost layer of these functional layers. In this regard, examples of this functional layer include an extremely thin antismudging layer, antistatic layer, or the like 1 nm or more and 50 nm or less.

At least any one of the layers included in the transparent laminatepreferably contains an ultraviolet absorber. An ultraviolet absorber that can be used is any known ultraviolet absorber.

With the transparent laminate, the surfaceA of the transparent laminateis not fogged as tested in an anti-fogging ability test in which the transparent laminateis left to stand in an environment of −15° C. for 5 minutes, then transferred to an environment of 20° C. or more and 25° C. or less and a relative humidity of 40% or more and 70% or less, and left to stand for 5 minutes. In the anti-fogging ability test, the environment of −15° C. can be achieved by a refrigerator. When the anti-fogging ability test is performed, a sample cut out of the transparent laminateis used. The size of the sample is 100 mm×100 mm. Then, this sample is bonded to a black acrylic plate 100 mm×100 mm×2 mm in size (for example, a product named “COMOGLAS Acrylic Sheet”, manufactured by Kuraray Co., Ltd.) with a transparent adhesive having a film thickness of 25 μm (a product named “PD-S1”, manufactured by Panac Co., Ltd.). This bond is done in such a manner that the back surface of the transparent laminate is the black acrylic plate side thereof, whereby the surface of the transparent laminate is made to be the observation side. Then, a piece formed in this manner is used as a measurement sample. The same measurement samples are produced, 3 sheets each. The measurement samples, 3 each (n=3), are used to perform each anti-fogging ability test. Whether the surface of the measurement sample (the surfaceA of the low-refractive-index layer) is not fogged is to be determined by visually observing the surface of the measurement sample immediately after the anti-fogging ability test is performed. In the anti-fogging ability test, the transparent laminateis left to stand in an environment of 20° C. or more and 25° C. or less and a relative humidity of 40% or more and 70% or less for 5 minutes, because there are some cases where the transparent laminateis not fogged immediately after being transferred to an environment of 20° C. or more and 25° C. or less, but is then fogged with time.

With the transparent laminate, the absolute value ΔY1 of a difference in the luminous reflectance Y of the surfaceA of the transparent laminatebetween before and after the above-mentioned anti-fogging ability test (|the luminous reflectance of the transparent laminate before the anti-fogging ability test−the luminous reflectance of the transparent laminate after the anti-fogging ability test|) is 0.2% or less. The luminous reflectance Y can be measured using a spectrophotometer (for example, a product named “UV-2600”, manufactured by Shimadzu Corporation). Specifically, a sample having the above-mentioned size is first cut out of the transparent laminate. Then, the spectrophotometer is used to radiate light at an incidence angle of 5 degrees to the surface (for example, the surfaceA of the low-refractive-index layer) of the sample before the anti-fogging ability test, receive the light reflected at the sample in the specular direction, and measure a reflectance in the wavelength range of from 380 nm to 780 nm. As used herein, the phrase “light at an incidence angle of 5 degrees” means light slanted at 5 degrees to the direction normal to the surface of the sample (the surface of the low-refractive-index layer), assuming that the normal direction is 0 degree. Then, the luminous reflectance Y is calculated with a software item (for example, a software item pre-installed in UV-2600) for conversion in terms of the brightness that a person senses with the eyes. Then, the sample undergoes the anti-fogging ability test. Then, the luminous reflectance Y of the sample after the anti-fogging ability test is determined in the same manner as the luminous reflectance Y of the sample before the anti-fogging ability test to determine the absolute value of a difference in the luminous reflectance Y of the surfaceA of the transparent laminatebetween before and after the anti-fogging ability test. The luminous reflectance of the transparent laminate before the anti-fogging ability test and the luminous reflectance of the transparent laminate after the anti-fogging ability test are each determined as the arithmetic average of the luminous reflectance values measured at 40 points in the sample, in which the 40 points for measurement are selected randomly. The upper limit of the ΔY1 is more preferably 0.2% or less, 0.15% or less, or 0.125% or less. The lower limit of the ΔY1 is 0% or more, or may be 0.03% or more.

With the transparent laminate, the absolute value ΔY3 of a difference in the luminous reflectance Y of the transparent laminatebetween before and after a light resistance test (|the luminous reflectance of the transparent laminate before the light resistance test−the luminous reflectance of the transparent laminate after the light resistance test|) is also preferably 0.5% or less, in which test light (for example, carbon arc lamp light) is radiated to the transparent laminatein an environment of 63° C. and a relative humidity of 50% for 200 hours. The light resistance test can be performed using a fade meter (for example, a product named “Ultraviolet Fade Meter U48AU”, manufactured by Suga Test Instruments Co., Ltd.). Specifically, a sample having the above-mentioned size is first cut out of the transparent laminate. Then, the spectrophotometer is used to determine a luminous reflectance Y before the light resistance test in the same manner as above-mentioned. Then, the sample is placed in the fade meter to undergo the light resistance test under the above-mentioned conditions. Then, the luminous reflectance Y of the sample after the light resistance test is determined in the same manner as the luminous reflectance Y of the sample before the light resistance test to determine the absolute value of a difference in the luminous reflectance Y of the surfaceA of the transparent laminatebetween before and after the light resistance test. The luminous reflectance of the transparent laminate before the light resistance test and the luminous reflectance of the transparent laminate after the anti-fogging ability test are each determined as the arithmetic average of the luminous reflectance values measured at 40 points in the sample, in which the 40 points for measurement are selected randomly. The upper limit of the ΔY3 is more preferably 0.5% or less, 0.4% or less, 0.3% or less, or 0.2% or less. The lower limit of the ΔY3 is 0% or more.

With the transparent laminate, the luminous reflectance Y of the surfaceA of the surfaceA that is yet to undergo the anti-fogging ability test and the light resistance test is preferably 3.5% or less. This allows the light transmittance of the whole transparent laminateto rise. Thus, for example, a facial transparent protector including the transparent laminatemakes it easier for a wearer of the facial transparent protector to see the other person or the like, and in addition, makes it easier for the other person to see the wearer. Furthermore, such a transparent laminate in an image display device enables the definition of an image to be enhanced. The luminous reflectance of the transparent laminate is determined as the arithmetic average of the luminous reflectance values measured at 40 points in the sample having the above-mentioned size, in which the 40 points for measurement are generally equally spaced so as to cover the whole transparent laminate. The luminous reflectance Y is more preferably 2.0% or less, 1.5% or less, or 1.2% or less, in terms of inhibiting the reflection of external light. In cases where the transparent laminateis used for a transparent shield film of a facial transparent protector, it is best that the luminous reflectance of each of the wearer side face (inner face) and the other person side face (outer face) of the facial transparent protector is low. At least having a lower luminous reflectance on the other person side face than on the wearer side face makes it possible to improve communication problems.

A ratio of a second peak intensity in a second wave number region of from 1150 cmto 1000 cmto a first peak intensity in a first wave number region of from 1780 cmto 1700 cm(the second peak intensity/the first peak intensity) is preferably 1.25 or more and 2.20 or less in an absorption spectrum obtained from the surfaceA of the transparent laminateby Fourier transform infrared spectroscopy (an FT-IR method). The peak in the first wave number region is a peak derived from an ester group, and the peak in the second wave number region is a peak derived from an ether group. Thus, having both a peak in the first wave number region and a peak in the second wave number region in the absorption spectrum means that the transparent laminate(for example, at least any one of the functional layeror the low-refractive-index layer) contains an ester component and an ether component such as an anti-fogging material. The ratio of 1.25 or more results in having a larger amount of an anti-fogging material containing an ether component, and thus, makes it possible to more enhance the anti-fogging ability and the flexibility. In addition, 2.20 or less results in not having too large an amount of an anti-fogging material containing an ether component, and thus, makes it possible to inhibit a decrease in hardness and a decrease in abrasion resistance. The ratio is preferably 1.30 or more and 2.20 or less, 1.35 or more and 2.20 or less, 1.40 or more and 2.20 or less, 1.25 or more and 2.15 or less, 1.30 or more and 2.15 or less, 1.35 or more and 2.15 or less, 1.40 or more and 2.15 or less, 1.25 or more and 2.10 or less, 1.30 or more and 2.10 or less, 1.35 or more and 2.10 or less, 1.40 or more and 2.10 or less, 1.25 or more and 2.00 or less, 1.30 or more and 2.00 or less, or 1.35 or more and 2.00 or less, 1.25 or more and 1.95 or less, 1.30 or more and 1.95 or less, or 1.35 or more and 1.95 or less. In particular, for example, in cases where the transparent laminateis used for a facial transparent protector, the ability to withstand dust and the like outdoors is required, but dust durability cannot be evaluated by a steel wool resistance test. Thus, when a falling sand abrasion test (ASTM D 968) is performed as a test in which dust is allowed to attack, the ratio of 1.30 or more and 1.95 or less makes it possible to have both a dust durability and an anti-fogging ability during actual usage, and accordingly, the ratio is more preferably 1.30 or more and 1.95 or less. In addition, the ratio may be 1.25 or more and 1.30 or less in order to more enhance the dust durability, and may be 1.95 or more and 2.20 or less in order to more enhance the anti-fogging ability.

In cases where a peak exists in a third wave number region of from 1540 cmto 1560 cmin an absorption spectrum obtained from the surfaceA of the transparent laminateby Fourier transform infrared spectroscopy (an FT-IR method) (for example, in cases where the transparent laminate contains a material having a urethane backbone), the ratio of the second peak intensity in the second wave number region of from 1150 cmto 1000 cmto the first peak intensity in the first wave number region of from 1780 cmto 1700 cmis preferably 0.01 or more and 0.4 or less. The ratio of 0.01 or more results in having a larger amount of an anti-fogging material containing an ether component, and thus, makes it possible to more enhance the anti-fogging ability and the flexibility. In addition, 0.4 or less results in not having too large an amount of an anti-fogging material containing an ether component, and thus, makes it possible to inhibit a decrease in hardness and a decrease in abrasion resistance. The ratio is preferably 0.03 or more and 0.4 or less, 0.05 or more and 0.4 or less, 0.01 or more and 0.35 or less, 0.03 or more and 0.35 or less, 0.05 or more and 0.35 or less, 0.10 or more and 0.35 or less, 0.01 or more and 0.30 or less, 0.03 or more and 0.30 or less, 0.05 or more and 0.30 or less, or 0.10 or more and 0.30 or less. In addition, the ratio may be 0.01 or more and 0.1 or less in order to more enhance the dust durability, and may be 0.3 or more and 0.4 or less in order to more enhance the anti-fogging ability.

A measurement by a Fourier transform infrared analysis method can be made as below-mentioned. First, a sample 10 mm×10 mm or larger in size is cut out of a transparent laminate. In addition, a background measurement is made using a measurement device composed of a Fourier transform infrared spectrophotometer (a product named “Nicolet iS10 FT-IR”, manufactured by Thermo Fisher Scientific Inc.) with a measurement accessory (a product named “Thunderdome”, manufactured by Spectra-Tech Inc.; ATR crystal, Ge; infrared incidence angle, 45°) attached, in which device no sample is placed. Then, the sample is placed in the measurement accessory with the measurement face of the sample facing the crystal side of the measurement accessory. Then, the knob of the presser jig is turned to bring the sample in sufficient contact with the crystal. Then, an absorption spectrum of the sample is checked on the monitor, and then, a measurement is started on the measurement device under the below-mentioned measurement conditions. From the background in the resulting absorption spectrum, the height to the peak top of each of the peak in the first wave number region and the peak in the second wave number region is determined using a computing software item accompanying the measurement device. From the results, the intensity ratio is calculated.

(Measurement Conditions)

The ester component is a component contained mainly in the functional layerand the low-refractive-index layer, and is derived from a polymer of an ionizing-radiation-polymerizable compound. The ether component is mainly a component contained in the below-mentioned anti-fogging material, for example, a component derived from an alkylene oxide in cases where the anti-fogging material is a material having an alkylene oxide such as ethylene oxide (EO), or a component derived from a polyether in cases where the anti-fogging material is a polyether-based urethane (meth)acrylate.

A ratio (Ra/Rz) of the arithmetic average roughness (Ra) to the maximum height (Rz) on the surfaceA of the transparent laminateis preferably 0.02 or more and 0.15 or less. For the sake of the anti-fogging ability, a larger surface area of the surface of the transparent laminate is more advantageous, and thus, the surface of the transparent laminate preferably has an irregular shape. However, this irregular shape, if too large, will undesirably cause glareproofness to be expressed, worsening the visibility. Because of this, to inhibit a decrease in the visibility and enhance the anti-fogging ability, the ratio is preferably 0.02 or more and 0.15 or less. That is, the ratio of 0.02 or more makes it possible to inhibit the glareproofness of the surfaceA of the transparent laminate, thus, making it possible to obtain favorable visibility. In addition, 0.15 or less makes it possible to enhance the anti-fogging ability. The ratio is more preferably 0.03 or more and 0.15 or less, 0.04 or more and 0.15 or less, 0.05 or more and 0.15 or less, 0.02 or more and 0.14 or less, 0.03 or more and 0.14 or less, 0.04 or more and 0.14 or less, 0.05 or more and 0.14 or less, 0.02 or more and 0.13 or less, 0.03 or more and 0.13 or less, 0.04 or more and 0.13 or less, 0.05 or more and 0.13 or less, 0.02 or more and 0.12 or less, 0.03 or more and 0.12 or less, 0.04 or more and 0.12 or less, or 0.05 or more and 0.12 or less.

The above-mentioned Ra and Rz are obtained by three-dimensionally extending a roughness as the two-dimensional roughness parameter described in the instruction manual (SPM-9600 February, 2016, P. 194-195) for the upgrade kit of a scanning probe microscope SPM-9600. Ra is determined in accordance with the following formula, wherein only the criterion length (L) is extracted from the roughness curve in the average line direction thereof, the average line direction of this extracted portion is taken as the X-axis, the longitudinal magnification direction is taken as the Y-axis, and the roughness curve is expressed as y=f(x).

Rz is a value obtained by extracting only the criterion length from the roughness curve in the average line direction thereof, and measuring the distance between the mountain-top line and the valley-bottom line of this extracted portion in the longitudinal magnification direction of roughness curve.

For the ratio, Rz and Ra are used for the below-mentioned reason. Ra is an average value obtained by calculating the area of all of the irregularities existing on the criterion length, and dividing the resulting value by the criterion length, and thus is not the average value of the actual irregularities. In addition, too small irregularities and too large irregularities, if any, are completely averaged, and thus, such noticeable irregularities cannot be measured. Rz is the maximum height, and thus, makes it possible to measure noticeable irregularities. Accordingly, Ra is used to know the size of the surface area, and Rz is used to know the limit value of the irregularities.

The Rz and Ra can be measured as below-mentioned. First, a sample 5 mm×5 mm in size is cut out of a transparent laminate. Then, using an atomic force microscope (Atomic Force Microscope, AFM) SPM-9700 manufactured by Shimadzu Corporation, the surface shape of the sample is measured on software SPM manager in the On-Line (measurement) mode under the following conditions. Then, the Off-Line (analysis) mode is used for image processing. The resulting AFM image is analyzed to obtain the Rz (maximum height) and Ra (arithmetic average roughness) of each sample. The arithmetic average of the Rz values and the arithmetic average of the Rz/Ra values are each determined from each of 14 points in each sample, and these average values are regarded as Rz and Rz/Ra.

(AFM Measurement Conditions)

The indentation hardness (H) at the surfaceA of the transparent laminateis preferably 20 MPa or more and 100 MPa or less. The indentation hardness His a value obtained by using an unloading curve to calculate a depth along which a measurement sample is in contact with an indenter (depth of contact), determining the area of contact from the depth of contact, and dividing the maximum load by the area of contact. The indentation hardness Hof 20 MPa or more makes it more difficult for the surfaceA of the transparent laminateto be scratched, and 100 MPa or less makes it possible to obtain favorable flexibility and favorable moldability. The indentation hardness Hmeasured at the surfaceA of the transparent laminateis preferably 25 MPa or more and 100 MPa or less, 30 MPa or more and 100 MPa or less, 20 MPa or more and 90 MPa or less, 25 MPa or more and 90 MPa or less, 30 MPa or more and 90 MPa, 20 MPa or more and 80 MPa or less, 25 MPa or more and 80 MPa or less, or 30 MPa or more and 80 MPa or less or less, and is particularly preferably 30 MPa or more and 80 MPa or less among these. In addition, the indentation hardness Hmay be 20 MPa or more and 30 MPa or less in terms of more enhancing the anti-fogging ability and affording moldability, and may be 80 MPa or more and 100 MPa or less in terms of enhancing the abrasion resistance.

The composite elastic modulus (Er) at the surfaceA of the transparent laminateis preferably 0.15 GPa or more and 1.5 GPa or less. The composite elastic modulus Er is a value calculated from the slope of an unloading curve. The composite elastic modulus Er of 0.15 GPa or more makes it more difficult for the surfaceA of the transparent laminateto be scratched, and 1.5 GPa or less makes it possible to obtain favorable flexibility and favorable moldability. The composite elastic modulus Er measured at the surfaceA of the transparent laminateis preferably 0.16 GPa or more and 1.5 GPa or less, 0.17 GPa or more and 1.5 GPa or less, 0.15 GPa or more and 1.45 GPa or less, 0.16 GPa or more and 1.45 GPa or less, 0.17 GPa or more and 1.45 GPa or less, 0.15 GPa or more and 1.40 GPa or less, 0.16 GPa or more and 1.40 GPa or less, or 0.17 GPa or more and 1.40 GPa or less, and is particularly preferably 0.25 GPa or more and 1.00 G or less. In addition, the composite elastic modulus Er may be 0.15 GPa or more and 0.25 GPa or less in terms of more enhancing the anti-fogging ability and affording moldability, and may be 1.0 GPa or more and 1.5 GPa or less in terms of enhancing the abrasion resistance.

The indentation hardness Hand the composite elastic modulus Er are measured by the below-mentioned method. First, a transparent laminate cut to 20 mm×20 mm in size is fixed to a commercially available slide glass via an adhesive resin (a product named “ARON ALPHA (registered trademark) for General Use”, manufactured by Toagosei Co., Ltd.) in such a manner that the surface side of the transparent laminate is the upper face. Specifically, a drop of the adhesive resin is placed in the center of a slide glass(a product named “Slide Glass (Strainer), 1-9645-11”, manufactured by AS One Corporation). In this step, the adhesive resin is not spread over the slide glass, and one drop of the adhesive resin is applied in such a manner that the adhesive resin does not extend beyond the transparent laminate when pressed and spread as described below. Subsequently, the transparent laminate cut to the above-mentioned size is brought in contact with the slide glass in such a manner that the surface side of the transparent laminate is the upper side, and that the adhesive resin is located in the center of the transparent laminate. Then, the adhesive resin is pressed and spread between the slide glassand the transparent laminate for temporary adhesion. Then, another new slide glassis placed on the transparent laminate to obtain a laminate composed of the slide glass, the adhesive resin, the transparent laminate, and the slide glass. Subsequently, a weight of from 30 g to 50 g is left to stand on the slide glassat room temperature for 12 hours. Then, the weight and the slide glassare removed from the laminate, and the rest is used as a measurement sample. The four corners of the transparent laminate fixed with the adhesive resin may further be fixed with tape (a product named “Cello-tape (registered trademark)”, manufactured by Nichiban Co., Ltd.). The measurement sample is fixed on the measurement stage of a microhardness tester (a product named “TI950 Tribolndenter”, manufactured by Hysitron Inc.) placed horizontally on an anti-vibration table. The measurement sample may be fixed by any method, for example, by fixing the four edges of the slide glasswith a tape (a product named “Cello-tape (registered trademark)”, manufactured by Nichiban Co., Ltd.) or the like as long as the measurement sample does not move. Additionally, in cases where the microhardness tester is equipped with an air suction system, the measurement sample may be fixed with the air suction system. After the measurement sample is fixed on the measurement stage of the microhardness tester, the indentation hardness Hand composite elastic modulus Er of the surface of the transparent laminate are each measured under the following measurement conditions. The indentation hardness Hand the composite elastic modulus Er are measured at five points freely selected at or near the center (the region where the adhesive resin exists) of the surface of the transparent laminate as the measurement sample to determine the arithmetic average of the resulting five hardness values. However, the five points to be freely selected for measurement should be selected from a portion as flat as possible in the transparent laminate by observing the transparent laminate at a magnification of 50 to 500 times under a microscope accessory to the TI950 TriboIndenter, avoiding areas with extreme protrusions and areas with extreme depressions on the contrary.

(Measurement Conditions)

The contact angle with water on the surfaceA of the transparent laminateis preferably 90° or more. That is, the surfaceA of the transparent laminateis preferably hydrophobic. This contact angle of less than 90°, which represents higher fittability with water, will undesirably lead to increasing the water absorptiveness (moisture absorptiveness), resulting in distorting or expanding the functional layer and the base material. In cases where this contact angle is 90° or more, water droplets, even if generated, will not be collected on the surface but run down, and a smudge such as a fingerprint is less likely to be left during processing. The contact angle with water on the surfaceA of the transparent laminateis measured using a microscopic contact angle meter (a product named “DropMaster 300”, manufactured by Kyowa Interface Science Co., Ltd.) in accordance with the sessile drop method described in JIS R3257: 1999. Specifically, a sample 25 mm×30 mm in size is first cut out of a transparent laminate. Then, this sample is flatly bonded onto a slide glass 50 mm×125 mm in size with a double-sided tape. Accordingly, the resulting object is a laminate composed of the slide glass, the double-sided tape, and the sample. Subsequently, the sample is exposed to ions from an ionizer (for example, a product named “KD-730B”, manufactured by Kasuga Denki, Inc.) for 30 seconds to eliminate static electricity on the sample and thereby to prevent static electricity on the sample from influencing the measurement result. After the static electricity is eliminated, 1 μL of water is dropped onto the surface of the sample (the surface of the low-refractive-index layer) using a syringe, and is left to stand for 5 seconds. Then, the microscopic contact angle meter is switched on to measure the contact angle with water. The contact angle is measured in an environment of a temperature of 20° C. or more and 25° C. or less and a relative humidity of 40% or more and 70% or less. The contact angle is measured at 10 different points, and the arithmetic average of the measured values is regarded as the contact angle of the surfaceA of the transparent laminate. The contact angle with water on the surfaceA of the transparent laminateis more preferably 90° or more and 130° or less, 90° or more and 125° or less, 90° or more and 120° or less, 92° or more and 130° or less, 92° or more and 125° or less, 92° or more and 120° or less, 95° or more and 130° or less, 95° or more and 125° or less, or 95° or more and 120° or less.

The transparent laminatepreferably has a total light transmittance of 90% or more. The transparent laminatehaving a total light transmittance of 90% or more makes it possible to obtain a sufficient optical performance. The transparent laminatemore preferably has a total light transmittance of 91% or more, or 92% or more. The upper limit of the total light transmittance of the transparent laminateis 100% or less.

The total light transmittance can be measured using a haze meter (for example, a product named “HM-150”, manufactured by Murakami Color Research Laboratory Co., Ltd.) by a method based on JIS K7361-1:1997 in an environment of a temperature of 23±5° C. and a relative humidity of 30% or more and 70% or less. The total light transmittance is determined as the arithmetic average of three measurements obtained from a sample 50 mm×100 mm in size cut out of a transparent laminateand set without any curl or wrinkle and without any fingerprint or dirt, in which the three measurements are made per sample. As used herein, the phrase “three measurements” refers not to three measurements made at the same point but to three measurements made at three different points. In the transparent laminate, the surfaceA is flat by visual observation, and the laminated layers such as the functional layerare also flat. In addition, the deviation of film thickness is also within +10%. Accordingly, it is considered that an approximate average total light transmittance of the whole surface of the transparent laminate can be obtained by measuring the total light transmittance at three different points of the cut-out sample. In cases where a sample having the above-mentioned size cannot be cut out of the transparent laminate, a sample 22 mm×22 mm or larger may be suitably cut out. In cases where the sample is smaller in size, three points of measurement should be secured by gradually shifting or turning the sample to such an extent that the light source spot is within the sample.

The transparent laminatepreferably has a haze value (total haze value) of 1% or less. The transparent laminatehaving a haze value of 1% or less makes it possible to obtain sufficient optical performance and transparency. The haze value can be measured using a haze meter (a product named “HM-150”, manufactured by Murakami Color Research Laboratory Co., Ltd.) by a method based on JIS K7136: 2000 in an environment of a temperature of 23±5° C. and a relative humidity of 30% or more and 70% or less. Specifically, the haze value is measured by the same method as the total light transmittance. The arithmetic average of three measurements is regarded as the haze value. The transparent laminatemore preferably has a haze value of 0.8% or less, or 0.5% or less. The lower limit of the haze value of the transparent laminateis 0% or more.

The surfaceA of the transparent laminatepreferably has a pencil hardness of H or harder. The surfaceA of the transparent laminate, having a pencil hardness of H or harder, makes it possible to enhance the durability. The pencil hardness test should be performed as follows: using a pencil hardness testing machine (a product named “Pencil Scratch Hardness Tester (electric type)”, manufactured by Toyo Seiki Seisaku-sho, Ltd.), a pencil (a product named “uni”, manufactured by Mitsubishi Pencil Co., Ltd.) is moved on the surface of a sample 50 mm×100 mm in size cut out of a transparent laminate, at a moving speed of 1.4 mm/second, in an environment of a temperature of 23±5° C. and a relative humidity of 30% or more and 70% or less while a load of 500 g is applied to the pencil. The grade of the hardest pencil that does not scratch the surfaceA of the transparent laminateduring the pencil hardness test is regarded as the pencil hardness of the surface. Different pencils with different hardnesses are used for the measurement of pencil hardness, and the pencil hardness test is repeated five times per pencil. In cases where no scratch is made on the surfaceA of the transparent laminatein four or more out of the five repeats, the pencil with the hardness is judged as making no scratch on the surfaceA of the transparent laminate. The scratch refers to that which is visibly detectable when the surfaceA of the transparent laminatesubjected to the pencil hardness test is observed under transmitting fluorescent light.

The thickness (total thickness) of the transparent laminatevaries depending on the use of the transparent laminate. In cases where the transparent laminateis used for an image display device, the transparent laminatepreferably has a thickness of 25 μm or more and 400 μm or less. This thickness provides easy handling (for example, favorable processability) as well as a sufficient function (for example, for making it more difficult to deform the transparent laminatedepending on the humidity and the temperature, thus maintaining the flatness that enables an image to be seen clearly) necessary for an image display device.

In cases where the transparent laminateis used for a facial transparent protector, the transparent laminateis required to be thinner and lighter, and thus, the transparent laminatepreferably has a thickness of 400 μm or less. In this use, the transparent laminate having too small a thickness is prone to be deformed, and is poorer in processability and handleability during wear. In addition, a long time wear causes a sense of discomfort in some cases. To inhibit this and make an attempt at more thinness and more lightness, the thickness of the transparent laminateis more preferably 30 μm or more and 400 μm or less, 40 μm or more and 400 μm or less, 25 μm or more and 300 μm or less, 30 μm or more and 300 μm or less, 40 μm or more and 300 μm or less, 25 μm or more and 200 μm or less, 30 μm or more and 200 μm or less, or 40 μm or more and 200 μm or less.

In cases where the transparent laminateis used for a transparent partition, the transparent laminateis required to be transparent and handleable for hand carry and the like, and thus, the transparent laminatepreferably has a thickness of 10000 μm or less. In terms of obtaining a self-standing ability and a degree of strength, and obtaining a more favorable transparency and a more favorable handleability, the thickness of the transparent laminatefor this use is more preferably 500 μm or more and 10000 μm or less, 1000 μm or more and 10000 μm or less, or 3000 μm or more and 10000 μm or less, 500 μm or more and 9000 μm or less, 1000 μm or more and 9000 μm or less, 3000 μm or more and 9000 μm or less, 500 μm or more and 8000 μm or less, 1000 μm or more and 8000 μm or less, 3000 μm or more and 8000 μm or less, 500 μm or more and 5000 μm or less, 1000 μm or more and 5000 μm or less, or 3000 μm or more and 5000 μm or less.

In cases where the transparent laminateis used for a transparent film curtain, the transparent laminateis required to provide easiness of attachment (handleability), lightness, flexibility, and strength, and thus, the transparent laminatepreferably has a thickness of 3000 μm or less. With the transparent film curtain, the easiness of attachment encompasses, for example, allowing the transparent film curtain to be less prone to break, for example, when the transparent film curtain is cut, perforated, or attached. In terms of obtaining a more favorable handleability and a more favorable strength and in terms of making an attempt at lightness and obtaining a favorable transparency, the thickness of the transparent laminatefor this use is more preferably 25 μm or more and 3000 μm or less, 30 μm or more and 3000 μm or less, 40 μm or more and 3000 μm or less, 25 μm or more and 800 μm or less, 30 μm or more and 800 μm or less, 40 μm or more and 800 μm or less, 25 μm or more and 400 μm or less, 30 μm or more and 400 μm or less, 40 μm or more and 400 μm or less, 25 μm or more and 200 μm or less, 30 μm or more and 200 μm or less, 40 μm or more and 200 μm or less.

The thickness of the transparent laminateis determined as the arithmetic average of the thickness values at 10 different points on the transparent laminate, in which the thickness values are measured at the 10 different points, for example, using a thickness measurement device (a product named “Digimatic Indicator IDF-130”, manufactured by Mitutoyo Corporation).